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Biology recaps > module 4 > Flashcards

module 4 Flashcards

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1
Q

Define Biodiversity

A
  • The variety of different species
  • The variation within a species
  • The variation of cell types
  • Within a single multicellular organism
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2
Q

Define a gene

A

Section of DNA, located at the locus, whose base sequence determines the sequence of amino acids in a polypeptide and functional RNA [rRNA and tRNA]

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3
Q

Give three differences between prokaryotic DNA and eukaryotic DNA

A

P – short, circular, not associated with histone proteins
E – long, linear, associated with histones

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4
Q

Describe the DNA in chloroplasts and mitochondria

A

Short, circular, not associated with histones [same as prokaryotes]

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5
Q

Give three words to describe the genetic code

A

Non-overlapping, universal, degenerate

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6
Q

Why is the genetic code evidence of evolution?

A

All species have the same genetic code - universal

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7
Q

How could the DNA and so RNA base sequence change and there be no change to protein tertiary structure?

A

The mutation may be a degenerate code. E.g. UAU and UAC are both Tyrosine. The Hydrogen, ionic and disulfide bonds would be the same.

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8
Q

Define an exon

A

Sequences within a gene that code for amino acid sequence. Always separated by at least one intron in eukaryotes

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9
Q

Define an intron

A

Non-coding multiple repeats, found between genes in eukaryotes

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10
Q

Define a genome

A

Complete set of genes in a cell

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11
Q

Define a proteome

A

Full range of proteins that a cell is able to produce

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12
Q

How is mRNA different to DNA?

A

Uracil replaces Thymine. Single stranded. No introns in eukaryotes

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13
Q

Describe Transcription

A
  • DNA helicase breaks Hydrogen bonds
  • DNA bases exposed on template strand.
  • RNA polymerase allows complementary RNA bases to align [A-U, G-C] and joins phosphodiester bonds.
  • Pre mRNA spliced to form mRNA.
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14
Q

Describe tRNA

A

Single strand RNA, held in a clover shape by Hydrogen bonds. Carries a specific Amino acid, dependent on anticodon sequence.

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15
Q

Describe Translation

A

-Ribosome binds to mRNA at start codon
- tRNA carries a specific aa dependent on anticodon sequence.
- If anticodon complementary to codon then amino acid will form peptide bond with other aa to form a polypeptide.
- Formation of peptide bond requires ATP.
- Two tRNA within each Ribosome at one time. - Continues until stop codon of mRNA reached

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16
Q

Mutations can spontaneously arise
during DNA replication. What can
increase the likelihood of mutations?

A

Mutagenic agents e.g. UV light, X Rays, Radiation or chemical carcinogens. Some viruses or bacteria can increase mutations.

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17
Q

Define non-disjunction

A

A form of mutation that can arise spontaneously in meiosis, results in too many or too few chromosomes in the gamete

18
Q

Define homologous chromosomes

A

A pair of chromosomes with the same genes but different alleles. The line up together in metaphase 1.

19
Q

Give the key principles of meiosis

A

Two nuclear divisions result in 4 haploid cells from 1 diploid parent cell. Genetically different daughter cells result from independent segregation and crossing over between homologous chromosomes.

20
Q

In an unfamiliar lifecycle diagram - what should you look out for to identify where meiosis occurs?

A

2n to n, diploid to haploid Formation of gametes or spores

21
Q

What does the expression 2n mean in
this context?

A

Possible number of different combinations of chromosomes following meiosis, not including crossing over. n=haploid number

22
Q

What does the expression (2 n)^ 2 mean
in this context?

A

Possible number of different combinations of chromosomes following random fertilisation of two gametes

23
Q

Give one further reason for genetic
variation within a species– other than
meiosis

A

Random fertilisation of haploid gametes

24
Q

Define Genetic diversity

A

Number of different alleles of genes in a population

25
Q

Give the principles of natural selection

A

Random mutations can result in a new allele. These can be advantageous that increase reproductive success. The advantageous allele is inherited by next generation. As a result the new allele increases in frequency in the population, over many generations.

26
Q

Give example of directional selection

A

Antibiotic resistance, increase in height [selecting for one extreme]

27
Q

Give example of stabilising selection

A

Human birth weight, number of eggs in next [selecting against extremes]

28
Q

Give an example of anatomical, physiological and behavioural adaptation

A

A – claws, sharp teeth, fur colour B – courtship, hibernation, migration P – fast metabolism, echolocation, venom

29
Q

Define a species

A

Organisms that can breed and produce fertile offspring

30
Q

What is the purpose of courtship behaviour?

A

Recognising same species, recognising gender, recognising sexual maturity, recognise synchronised gamete production. Form a pair bond.

31
Q

Define phylogenetic classification system

A

Arranges species into groups based on their evolutionary origins and relationships

32
Q

Define hierarchy

A

Smaller groups [taxa] are placed within larger groups, with no overlap

33
Q

Give the Taxa in order and give the mnemonic you will use.

A

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
Delicious King Prawn Curry or Fat Greasy Sausage

34
Q

What advances improved our understanding of phylogenetic classification?

A

Immunology and genome sequencing

35
Q

Define species richness

A

Number of different species in a community

36
Q

What does index of diversity tell us?

A

Relationship between species richness and number of individuals within a species

37
Q

How does modern farming reduce biodiversity?

A

Monoculture crops. Removal of hedgerows [allows for larger machinery]. Overgrazing. Use of herbicides and pesticides [Other plans compete for light, water, nutrients]

38
Q

Why should farmers want to increase biodiversity?

A

Monocultures susceptible to extinction. Hedgerows/field margins could increase predators to pests and provide pollinators. Reduce soil erosion.

39
Q

Why should society generally increase biodiversity?

A

Economic – organisms contribute to medicine, ecotourism and science. Environmental e.g. maintain CO2 absorption. Agricultural – monocultures susceptible to extinction. Aesthetic – beautiful to look at.

40
Q

How can you compare Genetic Diversity?

A

Measurable or observable characteristics, base sequences of DNA and mRNA, amino acids of proteins, immunological comparison

Biology recaps (2 decks)

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